A ready-to-cover (RTC) RC aircraft is a model that comes with pre-built main sections. However, it differs from the almost ready-to-fly planes in the sense that you have to cover the wings yourself with a film covering. This obviously requires extra time so expect about 30 to 50 hours depending on the aircraft model and experience.
Some extra tools are required: glue, cutting tools, paint, etc. It will take some extra time building the RC aircraft this way, but the result will be a plane with your own unique look.
Here you can see the "Edge 540 - 103" which is an example of an RTC model. The specs are listed below the picture.